Combustion apparatus



March 1932. E. R. sToNE COMBUSTION APPARATUS Filed Dec.

31, 1929 4 Sheets-Sheet INVENTOR MRS-roma CL. (P) ,W

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x ,x xzxx z ATTORNEY March vl, 1932. E. R. STONE GOMBUSTION APPARATUS Filed Dec. 31, 1929 4 Sheets-Sheet 2 INVENTOR ERRLLRaSTOHE- b !WM ATTORNEY E. R. STONE COMBUST ION 'APPA RATUS March l, 1932.

Filed Dec.

31, 1929 4 Sheets-Sheet 3 Pas-.5.

G: 3 ATTORNEY INVENTOR 'EnlR.5mom

Patented Mar. l, 1932 UNITED STATES P'ATENT' O FICE' EARLL E. STONE, OF LANSDOWNE, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELEGTRIC &7 MANUFACTURING COMPANY,'A CORPOBATION OF PENNSYLVANIA COMBUSTION .AIPABATUS App lcation'filed December 31, 1929. Serial No. 417,798.

My invention relates to combustion ap paratus and moreparticulary to underfeed stokers employing preheated air for supporting combustion, and it has for an object to 5 impove the efiiciency and Capacity of appara tus of this character. I

As is well known, the efiiciency of a stokerfired furnace can be increased app-reciably'by utilizing the waste heat ot' the flue gases to 10 heat the combustion air entering the furnace.

In installations of this character, the ifiue gases are conducted to some form of heat eX- ehanger through which the air for supporting combustion is passed A large portion of the heat of the fiue gases which would ordinarily be lost'is given up to the' air for supporting combustion and is returned tothe furnace thereby. v i

In apparatus of this character, heretofore known to me, the preheated air has been sup plied to the wind box beneath the stoker from which the air flowed through the grates in the usuai manner. Serious difficulties have been encountered in such apparatus for the reason that the preh'eated air within the wind-box Contacts with'the outer surface of the fuel teeding retorts' and' as a result the green coal within the retorts becomes too highly heated and tends to'fuse together. A fused mass of coal is difiioult to move. In fact, in extreme cases, thesecondary rams move back and forth within the retorts, without imparting any movement to such mass. Such conditions result in inefficient combustion, hothfor the reason that the required progressive movement of the fuel bed cannot be maintained and also for the reason thatsuch fused masses disrupt the fuel bed and cause' the stoker parts to burn out.

More particu1arly,' therefore, it is an object of this invention to provide-apparatusof this character, in which air at extremely high temperatures may be introduced into the combustion chamher, and, at the same time, the retorts and the coal within the retorts will be maintained in a relatively cool condition.

These and other objects are efected by my invention, as will be apparent from the foliowing description and claims taken in con nection with the accompanying drawings, fol-mine: a part of this application, in which:

Fig l is a Vertcai sectional View illustrat-` inga stoker-fired boiler furnace constructed in accerdance with the present invention;

Fig. 2 an enlarged fragmentary sectional view illustrating the Construction of the air supply apparatus for the stoker shown in Fig. l; i

Fig. 3 is a scctional View similar to Fig. 2, the section being taken through the center line of the tuyre rows of the stoker;

' Fig. 4 is a transverse section taken on` the line IV- lV of Fig. 2; i

Fig. 5 is a View similar to Fig. 3 illustrat-` inga modified form ofconstruction; and,

Fig. .6 is an enlarged transverse sectional :viewtaken on the line VI-VI of F ig. 5;

According to a preferred embodiment of the present invention, I provide a multiple retort underfeed stoker comprising spaced,` parallel retorts and tuyres bridging the space between adjacent retorts. I also pro-' Vide an open top rectangular box-like structure disposed between each of the adjacent retorts and directly beneath the tuyres; a conduit `connecting each *box-like structure with a manifold disposed exteriorly of the furnace; and means for supplying the manifold with preheated air under pressure. I provide the usual wind box beneath the stoker and' introduced into the wind box relatively cool air under pressure. Means is also provided for maintaining the pressure of air within the wind box at a greater valuethan the pressure :of air within the preheated air Conduit. v V

The cool air within the wind box Contacts with the exterior surface of theretorts and serves to maintain the walls thereof in a relatively cool condition. The preheated air flows through the tuyre rows and into the furnace without coming into contact with and overheating the retorts. As the pressure of the air within the wind box is greater than that of the preheated air, a circulation of cool air is maintained and such cool air mixes with the air coming from the box-like structure and fiows therewith through the tuyres.

Referring now in detail to the Construction illustrated, and particularly to Figs. 1 to 4, inclusive, it is to be observed that my invention is shown as incorporated in a conventional type of stoker-fired boiler furnace. The furnace comprises walls defining a combustion chamber 11, a boiler 12 disposed within. the upper portion of the chamber 11 and a multiple retort underfeed stoker 13 disposed within the lower portion of this chamber; r

The stoker 13 is 'of the combined underfeedoverfeed type and comprses an underfeed section 14 of alternately-arranged rows of troughs or retorts 15 and air-emitting grates or tuyres 16, and an overfeed Section 17 disposed at the discharge end of the underfeed section and including a series of grate members 18, 19, 20, 21 and 22 pivotally connected together'in end-to-end relation and extending in the direction of feel feed. In addition to the tuyres 16 a row of side wall tuyres 23 is .disposed at each side of the stoker for the purpose of protecting the side walls of the furnace and for admitting air for supporting combustion into'the combustion chamber. e

The retorts and tuyres of the underfeed section are constructed in the following well known manner. A plurality of angle beams 24 are disposed in'spaced parallelrelation and are supported at their upper ends by a transverse beam structure 25 disposed transversely of and beneath the front of the stoker, and at their lower ends by a second trans- Verse beam structure 26 disposed transversely of and beneath the lowerend of the und-erfeed section. The retorts 15 comprise side walls 27 and bottom walls 28 which are detachably Secured to alternate adjacent pairs of the beams 24. The tuyres 16 bridge the space between and are supported by the side walls 27 of adjacent retorts. The side wall tuyres 23 are supported by angle brackets 29, which are, in turn, supported from additional brackets 30, bolted to the side walls 27 of the extreme retorts.

Green fuel is fed from the usual hopper 31 and into the upper ends of the retorts 15 by primary rams 32 reciprocating within ram boxes 33. The fuel is advanced along the retorts and' upwardly and over onto the tuyres, by secondary rams 34 reciprocating within the retorts and supported by the bottom walls 28 thereof. The overfeed grate section 17 receives the burning material from tne underfeed section 14, agitates this material and positively moves such material thereover and into a clinker pit 35 disposed at the lower end of the overfeed section. The overfeed section is pivotally supported at its forward end to the underfeed section and is slidably supported at its rear end by the front wall of the clinker pit 35. The intermediate portions of the grate are supported by links 36 and 37. The

links 36 are for the purpose of supporting and permitting movement of the overfeed grate. The links 37 in addition to supporting the intermediate portions of the grate 17, provide for movement of the several grate members about their pivot-al connections.

As is common, a wind box or air chamber 38 is provided beneath the stoker. The air chamber is divided transversely by the supporting beam structure 26, thereby providing a front air chamber 39 beneath the underfeed section 14 and a rear air chamber 40 beneath the overfeed section 17.

As has been stated, it is a well known fact that the use of preheated air for supporting combustion in a furnace increases materially the efliciency of such apparatus. Also, it has been stated that, heretofore, diiiculty has been` experienced in installations using preheated air, for the reason that such air comes in contact with the outer surfaces of the retort side and bottom-walls and thereby causes thet reen coal within the retorts to become too' highly heated, which latter 'results in serious interference to the progressive'movement of the fuel.

I providea Conduit means for supplying preheated air directly to the under side of the tuyre rows, so that such air does not contact with the retort walls; As shown, open topped box-like structures 41 are disposed within the spaces between the sidewalls of adjacent retorts,and the upper portions of such boxes are disposed'closely adjacent the under side of the tuy`eres 16. A box-like structure 41 is also disposed 'between the side wall of each of the extreme retorts and the adjacent side wall of the furnace. The box-like structures 41 maybeheld in position by any suitable means, for example, by brackets 42 bolted to the sides of the box-like structures and to the angle be'ams 24. It Will be observed from an eXamination of Fig. 4' that spaces, indicatedby the reference numerals 43, are provided between the upper edges of the walls of the structures 41 and the tuyre rows, the purpose of which shall appear more fully' her'einafter.

Each of the box-like structures 41 is connected by a Conduit 44 to a manifold 45. Preheated air under pressure is supplied to the manifold 45 from a preheater 46 (Fig. 1) by a suitable conduit 47. The preheater 46 is of the conventional type and air at ordinary temperatures is supplied thereto from a fan 48 by a Conduit 49. This air is heated within the preheater by the hot flue gases from the furnace. A conduit 50 'connects the off-take of the furnace with the preheater, and a conduit 51 serves to convey the fiue gases from the preheater to a stack (not shown).

The exterior surfaces of the retort side and bottom walls and the supporting structure for such walls are maintained in a relatively cool condition by neans of the relatively cool air within the front air chamber 39. This cool air is supplied under pressure toi the chamber 39 by a conduit 52, which latter is connected to the exhaust of a cool air fan 53. The air is applied to the chamber 39 at a greater pressure than the pressure of the preheated air within the box-like structures 41 so that the cool air will pass through the spaces 43 between the upper edges of the boxi like structures and the tuyre rows, and flow through the tuyres and into the combustion' heated air will not afiect materially, the temi perature of the preheated air.`

Preheated air is supplied to the underside of the overteed grate section 17 by a'manifold 54' connecting the rear air chamber 40 with the lower end of the box-like structures 41, the' manifold being provided with spaced openings 54', each of which registers with an opening 41' provided in each of the box-like structures 41. The manifold 54 is provided with a damper 55 for controlling the flow of such air to the rear air' chamber. If desired cool air may also be supplied to the overfeed grate'section. As shown, the manifold 54 is provided with a damper-controlled opening 56, which communicates with the front air chamber 39. It will therefore be seen that the rear air chamber may be supplied ,with as mixture of relatively cool and preheated air, with preheated air alone or with relatively cool air alone, depending, of course, upon the results desired and'the Operating conditions. e

Means isialso. provided "for maintaining, automatically, a greater pressure of air within the cool air Conduit means, than the pressure of air within the preheated air Conduit means, so that there is a circulaton of cool air about the retorts at all times.

As shown in Fig. 1, I provide a damper 57 within the cool air conduit 52 and operate this damper by a reversing motor 58.; The operation of the motor is controlled by a switch mechanism 59, which latter operates in response to the changes in diiferential air pressure between the manifold 45 and the Conduit 52.

I provide, for example, a vessel6O containing a suitable liquid. 'A pair of bell jars 61 and 62`are disposed within the liquid and are connected by links 63 and 64, respectively, with the outer ends of a rocker arm 65. The interior of the bell jar 6l`is in communication with the manifold 45 by a pipe 65, and the interier of the bell jar 62 is in communication with the conduit 52 by a pipe 67.

An arm 68 extends from the rocker 65 and forms the novable element or contact of "the switch mechanism 59, the stationary elements of the switch being provided by. fixed Contacts 69 and 70. i

i ,An electric circuit 71 is connected to a suitable source of electrical energy (not shown). One leg of the circuit is connected to the ar-:

mature of themotor 58 by a lead 72, and the other leg of the circuit is connected to the arm 68 of the switch by a lead 7 3. The contacts 69 and 70 are connected to the motor by leads 74 and 75, respectively The motor is pret-c erably of the double wound seriestype, and` the leads 7 4 and'75 are connected to separate elds thereof. j

Should the differential pressure increase beyond a' predetermined amount, the bell jar' 62 moves upward, the rocker 65 moves n a counter-clockwise direction and causes the arni 68 to move to the left and engage the con tact 69.' n The current then fiows from one leg ot the circuit and through thelead 7 3, arm 68. contact 69, lead 74', one of the windings of the motor, the armature and back through the lead 72 to the other leg of the circuit. This causes the motor to rotate in adirection to close the damper 57. Should the difi'erential pressure decrease, the current fiows through the arm 68, the contact .70, lead 75, the other field of the motor, the armature and the lead 72, thereby causing the motor to rotate in the opposite direction and open the damper 57.

T he fans 48 and 53 are operatedso that normally the pressure within the frontair chamber 39 is at a predetermined greater amount than the pressure within the manif-old. I provide a simple means for varying the predetermined diterential air pressure; As

shown, the right-hand arm of the rocker 65' is provided ?with an extension 76 and a mov.-; able counter weight 77 is Suspended from the extension. By noving the counter weight along the extension, the predeterinined difieren'tial may be varied at will.

Referring now to Figs. 5 and 6, it will be' observed that I have shown a modified form of my invention in which the preheated air is supplied directly to the front air chamber beneath the underfeed section and cool air is supplied to the exterior retort walls and supportingstructure by means of a jacket Construction surrounding the retorts. The Construction and arrangement ot' the urnace, stoker, preheater, hot and cold air conduits and thecontrol mechanism are the same as in the previously described modification, and therefore a detail showing and description of these parts are considered unnecessary.

As shown, I provide an underfeed section 14a comprising retorts 15& and tuyres lGa. The retorts 15a comprise side walls 27@ and bottom walls QSasupported from angle'beans V front air chamber 39a.

and a bottom wall 82 is detachably Secured by bolts 83 to the lower edges of the side walls 81. The purpose of the detachable bottom wall is to facilitate the adjustment removal ,and replacement of parts of the retort aggregate such as the secondary ram mechanism. Each jacket structure is open' at each end to permit the flow of relatively cool air into the A cool air manifold 84 is disposed transversely beneath the underfeed section of the stokerand eonduits 85 connect the jacket structures with the manifold. A pipe 52a serves to supply the cool air to the manitold 84 from a suitable fan (not shown). The preheated air is supplied from the preheater (not shown) and directly to the front air chamber '39a by a conduit t'i 'ag The operation of the modified structure is the same as the structure previously described. The preheated air passes upwardly between adjacent acket struotures and through the tuyres into the furnace. The cool air at a greater pressure circulates about the retort side and bottom walls and its supporting structures, and flows out the ends of the jacket structures and into the front air chamber, thereby maintaining, at all times, the retort side and bottom walls in a` relatively cool condition so that the green coal within such retorts will not becometoohighly heated. While I have shown my invention in but two forms, it will be obviousto those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or asare specifically set forth in the appended claims.

hat I claim is: e

l. In combustion apparatus, the combination With an underfeed stoker comprising a fuel-feeding retort and an air-emitting grate; of conduit means for supplying preheated air to the grate; conduit'means for subjecting the walls of the 'retort to a stream of relatively cool air, whereby such walls are maintained at all times in a cool condition; and means providing for the fiow of air from the cool air conduit means to the preheated air conduit means.

2. In combustion apparatus, the combination with an underfeed stoker comprising a fuel feeding retort and `an air-emitting grate; of conduit means for supplying preheated air under a positive pressure to the grate; conduit means for supplying relatively cool air to the walls of the retort and having communication with the preheated air conduit means so that airpassing over the walls of the retort may enter the -latter conduit means; and means for supplying air to the cool air conduit means at a pressure greater than the pressure of the air within the preheated conduit means.

3. In conbustion apparatus, the combination with an underfeed stoker comprising a fuel feeding retort. and an air-emitting grate; of 'conduit means for supplying preheated air under pressure to the grate; conduit means for supplying relatively cool air under pressure to' the walls of the fuel feeding retort and having communicationwith thepreheated air conduit means so that air passing over the walls of' thereto't may enter the latter conduit means; and means for maintainng automatically the pressure of the air within the cool air conduit at a greater value than the pressure of the air within the preheated air conduit whereby the air 'Jill flow from the cool air conduit'to the preheated air conduit and maintain the walls of the retort at all times in a cool'condition.

-L Tn combustion apparatus, the combna ton with a multiple retort underfeed stoker coniprlsng parallel spaced retorts having side and bottom walls and tuyres .disposed between adjacent retorts; of conduit means for supplying preheated air under pressure to the under side of the tuyres; conduit means for subjecting the walls of the retort to a stream of relatively cool air under pressure and having communication with the preheated air conduit means so that air passing over the walls of the retort may enter the latter conduit means; and means for maintaining the air within the cool air conduit means at a greater pressure than that of the air within the preheated conduit means whereby there will be a flowof air from 'the cool air conduit to the preheated air conduit means.

5. In combustion apparatus, the combination witha multiple retort underfeed stoker comprising parallel spaced retorts having side and bottom walls and tuyres disposed between the retorts, and an ove'rfeed grate section disposed transversely of the discharge end of theunderfeed section; of conduit means for supplyng preheated air under pressure to the under side of the tuyres and to the under side of the overteed grate section; conduit means for subjecting the retort side and bottom walls to a stream of relatvely cool air under pressure and having` communication with the preheated air conduit means so that air passing over the walls of the retort may enter the latter conduit means; and means for maintaining the pressure-of air within the cool air conduit means at a greater value than the pressure of the air within the preheated air conduit means, whereby there will be a flow of air from the cool air conduit to the preheated air conduit means.

6. In combustion apparatus, the combination with an underfeed stoker comprising a fuel feeding retort and an air-emitting grate;

of means defining a wind box beneath the underfeed stoker; open top box-like structure 'disposed within the wind box and beneath the air-emitting grate; a conduit eXtending within the wind box and connected at its outer end to the box-like structure; means for suppiying relatively cool air under pressure to the wind box; means for supplying preheated air under pressure to the conduit; and means ;for maintaining the pressure of the air within the wind box at a greater value than the pressure of the air within the conduit.

7. In ccmbustion apparatus, the comhination of walis defining a combustion chamber; a stoker disposed within the lower portion of the ehamber' and including a fuel teeding retort and an air emitting grate; an air preheater utiiizing the fine gases of the furnace as a heating medium; means for supplying outside air to the preheater; conduit means for conveying the preheated air directly to the space beneath the grate so that such air may pass through the grate and into the coni bustion chamber for supporting comhustion; means providing a supply of relatively cool air under pressure; andconduit means other than said first-named conduit means connecting the cool air supply means with the walls of the retort so as to maintain the latter in a cooled condition.

8. In combustion apparatus, the combination of walls defining a combustion chanber; a stoker disposed within the lower portion of the chamber and including a tuel feeding retort and an air emitting grate; an air preheater utilizing the fine gases of the furnace as a heating medium; means for supplying outside air to the preheater; conduit means for conveying the preheated air directly to the space beneath the grate so that such air may pass through the grate and into the combustion chamber for supporting combustion; means providing a supply of relatively cool air under pressure; conduit means other than said first-named conduit means connecting the cool air supply means with the walls of the retort so as to maintain the latter in a cooled condition; and means providing for the flow of air from the cool air conduit means into the preheated air conduit means after such air has passed about the retort.

9. In combustion apparatus, the combination with a stoker of the type comprising parallel rows of retorts with rows of tuyres disposed therebetween; of means providing a supply of preheated air under pressure; conduit means connecting the preheated air sup ply means with the space beneath the tuyre rows so that such preheated air may pass through the tuyre rows for supporting combustion ;means providing a supply of relatively cool air .under pressure; and conduit means of the retort so that such cool air may come into contact with such walls and maintain the latter in a cooled condition.

10. In combustion apparatus, the combina tion with a stoker of the type comprising parallei rows of retorts with rows of tuyres disposed therebetween; of means providing a suppiy of preheated air under pressure; conduit means connecting the preheated air supply means with the space beneath the tuyre rows so that such preheated air may pass through the tuyre rows for supportin combustion'; means providing a supply o relatively cool air under pressure; conduit means other than the first-named conduit means.

connecting the supply of cool air with the walls of the retort so that such cool air may come into contact with such walls and maintain the latter in a cooled condition; and means providing for the flow of air from the cool air conduit means into the preheated air conduit means after it has passed about the retort.

In testimony whereof, I have hereunto subscribed my name this 10th day of Dec. 1929. v EARLL R; STONE. 

